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Empirical Spine received FDA Premarket Approval for its LimiFlex Dynamic Sagittal Tether in February, completing a decades-long journey from R&D to regulatory authorization. The motion-preserving system is indicated for the treatment of lumbar spinal stenosis associated with Grade I degenerative spondylolisthesis following decompression, creating a treatment category positioned between decompression alone and fusion.
Empirical Spine is expected to start its first surgeries with LimiFlex this month and is wrapping up a $25 million funding round to assist commercialization efforts.
We spoke with Louie Fielding, Co-Founder, President and Chief Operating Officer of Empirical Spine, about the company’s path to market and how LimiFlex meets the moment in spinal care. Mr. Fielding has led R&D on the technology since it started in the Stanford Biodesign Innovation program in the early 2000s.
Considering the market Empirical Spine is entering, Mr. Fielding said, “Today’s spine market reflects fierce competition in the face of commoditization and incremental innovation. LimiFlex is poised to make an end-run around this competition with a better alternative.”
What problem is LimiFlex solving? How does the design of the implant help solve the problem?
Mr. Fielding: Degenerative spondylolisthesis with stenosis is the most common indication for lumbar spinal fusion. Neural decompression relieves the primary patient symptoms of back and leg pain, but decompression alone has a high revision rate. As a result, decompression with instrumented fusion has become the dominant standard of care.
LimiFlex provides a motion-preserving treatment option for surgeons and patients. The design creates a tension band around two adjacent spinous processes, providing dynamic sagittal plane stabilization after decompression with shorter procedure time, less blood loss, faster discharge and faster recovery vs. fusion.
What are some of the important results you saw from your IDE study?
Mr. Fielding: Our study showed meaningful results for surgeons, systems, and most importantly, patients. Perioperatively, the LimiFlex procedure was much faster, with much lower blood loss compared to the fusion control group. Two-thirds of the LimiFlex patients in the trial were discharged the day of surgery, and nearly 90% were discharged by the first postoperative day, compared to a median three-night stay in the fusion control group. The data demonstrates that LimiFlex is truly an outpatient option for these patients.
At the two-year primary endpoint, the LimiFlex group had an overall higher composite clinical success (CCS) rate, 76.7% vs. 59.4% for study completers, and a reoperation rate at the index or adjacent levels of 7.2% for the LimiFlex group vs.10.9% for the control group. In our study, we defined the CCS as successful implantation, improvement of at least 15 points on the Oswestry Disability Index, absence of a decrease in neurological status, absence of additional surgical intervention, and absence of device integrity failures. The study was powered for noninferiority, which was met by a large margin.
An upside to the length of the PMA process is that our five-year data collection is almost complete, and those results are durable to five years.
The ASC market is expected to see meaningful growth in the coming years. When did the outpatient market factor into your strategy?
Mr. Fielding: Nobody was thinking about outpatient spine surgery when we started working on LimiFlex at Stanford. It has been fortuitous that LimiFlex is perfectly set up for the ASC market.
Almost all patients with degenerative spondylolisthesis are receiving spinal fusions during an inpatient procedure. Our procedure opens up an enormous patient population for those surgeons to shift the site of treatment into their surgery center, where they have more control and can offer their patients a concierge like surgical experience. LimiFlex is also saving payors money because it’s shifting a high acuity inpatient procedure to the outpatient setting.
What does your commercialization plan look like?
Mr. Fielding: For 2026, we are focusing on a limited market release to develop the LimiFlex market and sales model at key accounts and regions. These will include several IDE study investigators and surgeon practices with access to ASCs.
While we’re focusing on growing accounts and converting more surgeons, it will also be important to funnel patients to surgeons who are performing the LimiFlex procedure. When patients are told they need a fusion, they go straight to the internet to research their options. We’re looking at setting up referral pathways to get the right patients to the right centers, so that they are screened appropriately, receive conservative care, and then have surgery with a well-qualified provider.
What does the reimbursement landscape look like for you?
Mr. Fielding: We have identified an established CPT code with a defined Medicare benefit category, which was used successfully during the IDE trial, and are collaborating with the specialty societies to optimize coverage and physician payment. Facility reimbursement is very good across all settings: ASC, outpatient, and inpatient. We look forward to working with private payors to demonstrate cost effectiveness of the LimiFlex procedure.
What challenges did you have to overcome to make LimiFlex a minimally invasive, outpatient surgical option?
Mr. Fielding: The biggest challenges to bringing to the market a novel option for degenerative spondylolisthesis with stenosis have been the length of the PMA process and the financing environment in orthopedics and spine. We are fortunate to have a team and investors who believe in our mission and technology and have shown a great deal of resolve through this process.
It was a long journey to FDA Premarket Approval for LimiFlex. How has the spine market changed over time?
Mr. Fielding: Enabling technology, including image guidance, robotics, and augmented reality, has been a major trend since we first started working on LimiFlex. These amazing technologies are primarily used to improve accuracy and efficiency of fusion procedures, while fusion products (implants, grafts, and biologics) have become an increasingly competitive arena with significant price pressures.
LimiFlex represents a novel, motion-preserving, outpatient treatment option that bypasses these expensive technologies with much faster recovery and durable patient outcomes. Our recovery rates are 90% in the first three months after surgery versus around 50% for fusion patients. We’re able to give patients a massive amount of their lives back, which other technologies can’t do.
What advice would you give other entrepreneurs with innovative technology?
Mr. Fielding: Make sure that your product meets a clinical need and is not just another hammer looking for a nail. There is significant pent-up need for innovation in the spine market. Surround yourself with good people and challenge each other to do amazing things.
Empirical Spine received FDA Premarket Approval for its LimiFlex Dynamic Sagittal Tether in February, completing a decades-long journey from R&D to regulatory authorization. The motion-preserving system is indicated for the treatment of lumbar spinal stenosis associated with Grade I degenerative spondylolisthesis following decompression,...
Empirical Spine received FDA Premarket Approval for its LimiFlex Dynamic Sagittal Tether in February, completing a decades-long journey from R&D to regulatory authorization. The motion-preserving system is indicated for the treatment of lumbar spinal stenosis associated with Grade I degenerative spondylolisthesis following decompression, creating a treatment category positioned between decompression alone and fusion.
Empirical Spine is expected to start its first surgeries with LimiFlex this month and is wrapping up a $25 million funding round to assist commercialization efforts.
We spoke with Louie Fielding, Co-Founder, President and Chief Operating Officer of Empirical Spine, about the company’s path to market and how LimiFlex meets the moment in spinal care. Mr. Fielding has led R&D on the technology since it started in the Stanford Biodesign Innovation program in the early 2000s.
Considering the market Empirical Spine is entering, Mr. Fielding said, “Today’s spine market reflects fierce competition in the face of commoditization and incremental innovation. LimiFlex is poised to make an end-run around this competition with a better alternative.”
What problem is LimiFlex solving? How does the design of the implant help solve the problem?
Mr. Fielding: Degenerative spondylolisthesis with stenosis is the most common indication for lumbar spinal fusion. Neural decompression relieves the primary patient symptoms of back and leg pain, but decompression alone has a high revision rate. As a result, decompression with instrumented fusion has become the dominant standard of care.
LimiFlex provides a motion-preserving treatment option for surgeons and patients. The design creates a tension band around two adjacent spinous processes, providing dynamic sagittal plane stabilization after decompression with shorter procedure time, less blood loss, faster discharge and faster recovery vs. fusion.
What are some of the important results you saw from your IDE study?
Mr. Fielding: Our study showed meaningful results for surgeons, systems, and most importantly, patients. Perioperatively, the LimiFlex procedure was much faster, with much lower blood loss compared to the fusion control group. Two-thirds of the LimiFlex patients in the trial were discharged the day of surgery, and nearly 90% were discharged by the first postoperative day, compared to a median three-night stay in the fusion control group. The data demonstrates that LimiFlex is truly an outpatient option for these patients.
At the two-year primary endpoint, the LimiFlex group had an overall higher composite clinical success (CCS) rate, 76.7% vs. 59.4% for study completers, and a reoperation rate at the index or adjacent levels of 7.2% for the LimiFlex group vs.10.9% for the control group. In our study, we defined the CCS as successful implantation, improvement of at least 15 points on the Oswestry Disability Index, absence of a decrease in neurological status, absence of additional surgical intervention, and absence of device integrity failures. The study was powered for noninferiority, which was met by a large margin.
An upside to the length of the PMA process is that our five-year data collection is almost complete, and those results are durable to five years.
The ASC market is expected to see meaningful growth in the coming years. When did the outpatient market factor into your strategy?
Mr. Fielding: Nobody was thinking about outpatient spine surgery when we started working on LimiFlex at Stanford. It has been fortuitous that LimiFlex is perfectly set up for the ASC market.
Almost all patients with degenerative spondylolisthesis are receiving spinal fusions during an inpatient procedure. Our procedure opens up an enormous patient population for those surgeons to shift the site of treatment into their surgery center, where they have more control and can offer their patients a concierge like surgical experience. LimiFlex is also saving payors money because it’s shifting a high acuity inpatient procedure to the outpatient setting.
What does your commercialization plan look like?
Mr. Fielding: For 2026, we are focusing on a limited market release to develop the LimiFlex market and sales model at key accounts and regions. These will include several IDE study investigators and surgeon practices with access to ASCs.
While we’re focusing on growing accounts and converting more surgeons, it will also be important to funnel patients to surgeons who are performing the LimiFlex procedure. When patients are told they need a fusion, they go straight to the internet to research their options. We’re looking at setting up referral pathways to get the right patients to the right centers, so that they are screened appropriately, receive conservative care, and then have surgery with a well-qualified provider.
What does the reimbursement landscape look like for you?
Mr. Fielding: We have identified an established CPT code with a defined Medicare benefit category, which was used successfully during the IDE trial, and are collaborating with the specialty societies to optimize coverage and physician payment. Facility reimbursement is very good across all settings: ASC, outpatient, and inpatient. We look forward to working with private payors to demonstrate cost effectiveness of the LimiFlex procedure.
What challenges did you have to overcome to make LimiFlex a minimally invasive, outpatient surgical option?
Mr. Fielding: The biggest challenges to bringing to the market a novel option for degenerative spondylolisthesis with stenosis have been the length of the PMA process and the financing environment in orthopedics and spine. We are fortunate to have a team and investors who believe in our mission and technology and have shown a great deal of resolve through this process.
It was a long journey to FDA Premarket Approval for LimiFlex. How has the spine market changed over time?
Mr. Fielding: Enabling technology, including image guidance, robotics, and augmented reality, has been a major trend since we first started working on LimiFlex. These amazing technologies are primarily used to improve accuracy and efficiency of fusion procedures, while fusion products (implants, grafts, and biologics) have become an increasingly competitive arena with significant price pressures.
LimiFlex represents a novel, motion-preserving, outpatient treatment option that bypasses these expensive technologies with much faster recovery and durable patient outcomes. Our recovery rates are 90% in the first three months after surgery versus around 50% for fusion patients. We’re able to give patients a massive amount of their lives back, which other technologies can’t do.
What advice would you give other entrepreneurs with innovative technology?
Mr. Fielding: Make sure that your product meets a clinical need and is not just another hammer looking for a nail. There is significant pent-up need for innovation in the spine market. Surround yourself with good people and challenge each other to do amazing things.
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Carolyn LaWell is ORTHOWORLD's Chief Content Officer. She joined ORTHOWORLD in 2012 to oversee its editorial and industry education. She previously served in editor roles at B2B magazines and newspapers.
